Background: Since the 2005 consensus, a limited number of studies have validated the prognostic value of the modified Gleason grading system (MGS). We compared the biochemical recurrence (BR) following radical prostatectomy (RP) of two chronologically different groups of patients: needle biopsies graded before and after the modified Gleason grading system.Design: Group 1 comprised 197 consecutive patients submitted to radical prostatectomy with needle prostatic biopsies (NPB) graded according to the standard Gleason system in the period 1997/2004; and Group 2, 176 consecutive patients with NPB graded according to the MGS in the period 2005/2011. Three prognostic factors were analyzed: Gleason biopsy score, preoperative serum PSA, and clinical stage (T1c/T2). Time to biochemical recurrence following RP was analyzed with the Kaplan-Meier product-limit analysis using the log-rank test for comparison between the groups and prediction of time to BR using univariate and multivariate Cox proportional hazards model.Results: There was no difference between the groups related to age and race. The mean number of cores was 8 and 11 for Groups 1 and 2, respectively. Group 1 had significantly more patients in clinical stage T2 (p<0.01), higher preoperative PSA (p=0.03), and a higher total percentage of length of cancer in mm in all cores (p=0.03). The mean Gleason score was 6.3 and 6.5 for Groups 1 and 2, respectively. Time to BR was significantly shorter in Group 2 (log-rank, p=0.01). In univariate analysis only Gleason biopsy grading in Group 2 was significantly predictive of time to BR (hazard ratio 2.21, confidence interval, 1.26-3.90, p=0.01). In multivariate analysis including preoperative PSA and clinical stage, only Gleason grading in Group 2 was independent predictor of BR (hazard ratio 2.21, confidence interval 1.26-3.90, p=0.01).Conclusions: The patients in Group 2 (2005/2011) reflect the time-related changes: higher clinical stage T1c, lower preoperative serum PSA, and lower total percentage of length of cancer in all cores. However, using the modified Gleason system, the Gleason score was higher in Group 2. Only in Group 2, Gleason grading significantly predicted time of BR in univariate analysis and was independent predictor in multivariate analysis. The results favor that the 2005 ISUP revision is a refinement of the Gleason grading.Category: Genitourinary (including renal tumors)